Vertical
and Horizontal Gates:
Gates
are described according to the direction of their set, relative to the
"fall line". The "fall line" is the path of steepest
descent, that can otherwise be thought of as the path that a soccer ball would
travel if released from any given spot on the hill. If the gates are set along
the fall line, so that the gate line runs parallel to the fall line, they are
set vertically. If the gates are set across the fall line, so that the gate line
runs perpendicular to the fall line, they are set horizontally.